﻿<!DOCTYPE html>
<html lang="en">
<head>
    <title>使用闭包统计计数</title>
</head>
<body>
    <p>局部变量计数</p>
    <button type="button" onclick="myFunction()">计数!</button>
    <p id="demo">0</p>
    <script>
        let add = (function () {
            let counter = 0;
            return function () { 
                return counter += 1; 
            }
        })();
        function myFunction() {
            document.getElementById("demo").innerHTML = add();
        }
    </script>
</body>
</html>
